Carbon nanotube (hereinafter referred to as “CNT”) has high heat and electrical conductivity, high corrosion resistance, and the like and has been attracting attention as a novel material.
The CNTs are produced as follows, for example: a layer containing a substance serving as a catalyst for generating the CNTs is formed on a substrate; a heat treatment is performed on the layer, to generate a large number of catalyst particles on the substrate; and gas serving as a raw material for the CNTs is supplied to the catalyst particles, to allow the CNTs to grow on the catalyst particles. In this production method, the catalyst particles move when the CNTs grow, and hence it is difficult for the CNTs to grow vertically with respect to the surface of the substrate. For this reason, development of a holding structure capable of holding catalyst particles on a substrate has been progressed.
Patent Literature 1 discloses a method for producing a holding structure, including the following steps: stacking an Al layer containing oxygen, a buffer layer made from Si, and a Fe layer in this order on a barrier layer formed on a surface of a substrate; then performing a heat treatment on the multilayer structure, to form a holding structure, in which fine Fe particles serving as catalyst particles are held by being partially embedded in the buffer layer.